Fire sensors such as smoke detectors and heat detectors are among the most effective devices for providing early warning of danger associated with fires. Nevertheless, because fire sensors typically provide highly reliable smoke detection at the earliest presence of fire, they are also susceptible to false alarms. Responding to false alarms wastes critical financial and equipment resources of emergency responders, places the safety of the emergency responders and that of citizens in the response path at risk, and can divert emergency responders away from actual emergencies.
False alarms are also costly to businesses. Businesses suffer productivity losses due to the downtime associated with false alarms. In addition, emergency responders such as fire departments are increasingly charging businesses for the cost associated with responding to false alarms.
Moreover, many individuals have become accustomed to false alarms. The nuisance associated with false alarms can cause individuals to ignore future fire alarms. As a result, adoption and use of fire sensors in settings such as residences and business premises is declining due to the high incidence of false alarms generated by smoke detectors in the premises.
Fire sensors are often wired to a building network system that includes a fire alarm control panel or monitoring system. When a fire sensor detects heat and/or smoke, the fire sensor sends an alarm signal indicative of fire, such as a smoke level or an alarm state, to the monitoring system. In response, the monitoring system issues a general fire alarm signal and contacts emergency responders via an emergency telephone network (e.g. 911), for example.
False alarms occur for a number of reasons. In one example, dirt and dust that has accumulated on or within the fire sensors can interfere with normal detector operation. This can occur in residential settings as well as in commercial or municipal settings. For example, dirt and dust caused from trains entering a train station can cause fire sensors installed on train platforms to register false alarms if the fire sensors are not regularly maintained. In another example, aging fire sensors that have not been replaced within the manufacturer's recommended replacement period (e.g. 10 years) can cause false alarms. In yet another example, the fire sensors are improperly situated near high humidity areas such as bathrooms, the high humidity of which can trigger false alarms.
In still another example of false alarms generated by fire sensors, a fire sensor installed in a kitchen area correctly detects a release of smoke from food items cooking in the kitchen area (e.g. bread in toaster, skillet on a stove). In many cases, an initial fire threat associated with food in a kitchen area detected by a fire sensor is a transitory threat that can usually be eliminated by an individual present in the kitchen. However, because the signal indicating the fire event has already been sent by the fire sensor to the monitoring system, the monitoring system issues the general fire alarm and contacts emergency responders to respond to the threat.
Traditional approaches to minimizing false alarms have typically focused on improving the capabilities of the fire sensors. Improvements to fire sensors include incorporating multiple sensors (e.g, optical, ionization) into the devices and by using advanced smoke detection algorithms. However, these improvements have not significantly reduced the number of false alarms.